Various medications are often supplied using cartridge-needle units and a syringe adapter. The cartridge-needle units include a barrel having a piston at one end and a needle assembly at the other with the pharmaceutical to be injected housed within the syringe barrel between the piston and the needle assembly. The adapter typically includes a hollow body sized to hold the barrel of the cartridge-needle unit and a stem designed to engage the piston. The cartridge-needle unit is mounted within the adapter body and the injection is given. After use, the cartridge-needle unit is disposed of while the body and stem of the adapter can be reused.
One of the problems with health care delivery is risk of infectious diseases being spread through accidents, especially needle sticks, with used syringes. There have been many attempts to create safety syringes in which the needle is either manually or automatically drawn into the barrel or other housing of the syringe after use. However, these designs have not fully addressed the problems associated with the safe disposal of conventional cartridge-needle units after use.